Ultrasonic fuel level sensor

[AlfettaResto]

Hi, I'm converting my 76 Alfetta GT to a twin spark but I'm having a problem with the standard fuel level float sensor.  I'm using the Alfa 75 fuel sending unit with the in tank fuel pump and was trying to use the standard float sensor with that but other than drilling holes in the tank for the wires I can't see any other way that would work.  Problem is I don't want to drill any holes in the tank for obvious reasons.  I have recently been reading about ultrasonic fuel level sensors and was wondering if anyone has used them on their car.  Were they any good and can you connect them to the existing fuel gauge or do you have to run with the digital display provided?  Any other suggestions are welcome.

[jazig.k]

You're gonna need to mount it on the top looking down at the fuel (at work they all mount up top looking down to reflect off the surface). The output signal would then need to be translated from whatever the signal (linear scale 4-20mV output in my experience) to a voltage/resistance the equivalent of the Alfa GT, which I posted the Ohms of multiple positions in a thread here when I repaired 2 faulty sender's. Playing with a gauge and running test bench voltage through it to see what the exact position of voltage is would be most accurate.

You're going to need to dampen the output to the gauge too, to slow down the response time from the sloshing of fuel moving in the tank. Maybe already figured out in these ones you're looking at? But central tank mounting would be ideal to minimising this in your installation.

And possibly, it won't like being wet and dripping. A fill cycle from a spray ball in a tank disables the wave radar and runs on a calculation of flowrate/minutes plus time allowed for sensor to drip bulk of the fluid off. Also might be sorted out in what you're looking at.

[AlfettaResto]

Thanks for getting back to me Jazig.  I thought the sensor had to be on top of the tank to but the videos I've seen for some of the sensors appear to be on the bottom of the tank looking up which would be my preference otherwise I'd need to cut a hole in the boot floor to accommodate it. They were a Chinese branded sensor so I'm not confident they got it right.  Would you know if there are sensors that work from the bottom of the tank looking up?

[jazig.k]

No reason it couldn't be made to mount constantly submerged looking up. 
Speaking to someone who knows audrinos would be the way to go getting signal converted I'd think. I don't know much about them but they seem pretty good at that sort of thing. Might already be something on the market too if you look around.